October 11, 2011 — Frequent use of aspirin is associated with early aging macula disorder (AMD), as well as wet late AMD, and risks for those problems appear to be linked to how often aspirin is consumed.

Those findings are from a study of nearly 4700 European patients aged 65 years or older that was published online September 13 in Ophthalmology.

"Associations between aspirin use and AMD have been addressed in various settings with inconsistent results," write Paulus T.V.M. de Jong, MD, PhD, from the Netherlands Institute for Neuroscience and Academic Medical Center, Amsterdam, and colleagues.

To find out more about that possible association, Dr. de Jong and colleagues conducted a cross-sectional, population-based study using structured interviews to assess aspirin use and AMD in 4691 people who lived in 7 European countries: Norway, Estonia, United Kingdom, France, Italy, Greece, and Spain.

In addition to being queried about their aspirin use, the participants were also asked about their sociodemographic status, educational level, current and past smoking history, and consumption of alcohol. Other questions focused on their medical history, including history of stroke or myocardial infarction, and whether they had been diagnosed with either angina or diabetes mellitus.

Aspirin use was gauged using a precoded response category of 7 options that ranged from "never" to "daily."

Cholesterol levels were also determined using fasting blood samples.

Digitized fundus images were then obtained from participants, and the images sent to a grading center and evaluated by 2 experienced staffers. The images were graded according to the International Classification and Grading System for Age-Related Maculopathy and AMD.

The researchers defined dry AMD as any sharply demarcated round or oval area of apparent absence of the retinal pigment epithelium, with the largest diameter more than 175 μm, with visible choroidal vessels, and with no presence of wet AMD.

Wet AMD was defined as the presence of a serous or hemorrhagic detachment of the retinal pigment epithelium, a subretinal neovascular membrane, subretinal hemorrhage, periretinal fibrous scarring, or a combination of those characteristics. That definition held even when fundus images showed patches of dry AMD.

The authors report that 36.4% of the participants had evidence of early AMD and 3.3% had evidence of late AMD.

"For daily aspirin users, the [odds ratios], adjusted for potential confounders, showed a steady increase with increasing severity of AMD grades," the researchers write. "When adjustment was made for all known confounders including [cardiovascular disease] or angina, the associations did not change. However, there may be other confounders that were not measured," they write.

The authors advise caution in interpreting the results of the study. "This was a cross-sectional study, and the possibility that people with AMD took aspirin after experiencing visual problems cannot be excluded," they note. Another limitation is that “[i]t is possible that participants incorrectly reported their [cardiovascular disease] history, leading to residual confounding and measurement error.” However, the authors say, "[t]he protocol attempted to minimize misreporting by asking about serious events such as heart attack and stroke and also recorded the date of the event."

Even with the limitations of the study, however, the authors conclude, "[t]his interesting observation warrants further evaluation of the associations between aspirin use and AMD."

The study was supported by the European Commission Vth Framework, Brussels, Belgium. Funding for cameras was provided by the Macular Disease Society UK. Additional funding in Alicante, Spain, was provided by the Spanish Ministry of Health, Madrid, and CIBER de Epidemiologi’ y Salud Publica and the Generalitat Valenciana, both in Valencia. One author received support from the Estonian Ministry of Education and Science. The authors have disclosed no relevant financial relationships.